Alkaline storage batteries such as nickel-metal hydride storage batteries, nickel cadmium storage batteries, etc. are superior in weight saving by miniaturization and widely used as electric sources of personal computers, portable telephones, etc.
In many cases, a plurality of these alkaline storage batteries are used in the form of battery packs, and the respective alkaline storage batteries are required to have a uniform charge and discharge capacity with no variation.
In order to make uniform the capacity of batteries, it is necessary that a positive electrode plate used in, for example, nickel-metal hydride storage batteries is constructed by filling a metallic porous body with a nickel hydroxide active material as uniform as possible. As specific methods for filling the metallic porous body with an active material, there have been a method of filling the metallic porous body with a pasty active material by jetting from a nozzle the pasty active material against one face toward another face of the metallic porous body in such a manner that the active material does not pierce through the metallic porous body, a method of filling the metallic porous body by dipping it in a pasty active material, etc. as disclosed in JP-A-9-106814, etc.
The metallic porous bodies filled with the active material are controlled with measuring the weight of the filled active material by penetrating a radiation such as β-rays through the metallic porous bodies as shown in FIG. 6.